1. Field of the Invention
The invention relates to an improved electronically regulatable vehicle brake system with traction control, of the kind shown in a hydraulic circuit diagram in FIG. 1 of German Patent Disclosure DE 196 39 563 A1, for example.
2. Description of the Prior Art
The known electronically regulatable vehicle brake system mentioned above has a master cylinder, which is actuated by the driver and connected indirectly to a hydromechanical wheel brake via a so-called hydraulic unit. The hydraulic unit receives electromagnet valves and an externally drivable pressure generator, in order to modulate the brake pressure individually at each wheel. For this purpose, the pressure generator is connected by its intake side to an intake line that leads to the master cylinder, and this intake line is controllable by means of a triggerable switching valve. Brake pressure modulation can optionally be done independently of the driver. The goal of this is for any wheel slip that occurs at the wheels of the vehicle to be avoided by means of a brake pressure buildup or reduction, since when wheel slip occurs, unstable driving states may be involved that can be controlled by the driver only with difficulty. Triggering the components of the hydraulic unit is done by means of an electronic control unit, which for the purpose assesses measurement parameters, from wheel rotation or pressure sensors, among others, and converts them into appropriate trigger signals.
A disadvantage of the electronically regulatable vehicle brake system with traction control is that the speed at which a buildup of a brake pressure by the pressure generator takes place is too slow for certain brake pressure regulating functions, especially at low ambient temperatures, when the pressure fluid has high viscosities. Moreover, the flow cross sections in the system represent hydraulic resistances that must be overcome by the pressure generator. Particularly the cross sections of the brake lines cannot be increased arbitrarily, because otherwise difficulties arise in bending and handling such brake lines during vehicle assembly.